1. Field of the Invention
The present invention relates to a method and system for managing terminals in a network computing system where a host computer and a plurality of terminals are interconnected via a front-end processor. More specifically, it relates to a method and system for managing terminals to enable a host computer to have terminal status information updated in a timely manner for indicating which terminals are in session and whether the terminals in session are activated for transaction or not.
2. Description of the Related Art
The recent trend toward open system architecture in computer system solutions requires flexibility in networks to enable a diversity of host computers and terminals having different interfaces to be connected with each other. Such flexibility has been achieved using front-end processors between host computers and terminals to bridging a gap in their interface.
In a network computing system equipped with such front-end processors, each terminal establishes an active connection with a front-end processor associated thereto when the terminal (or a user of the terminal) logs into the system. In other words, a "session" is activated between the terminal and front-end processor. Since only the terminals in session can communicate with their upper layer computers, it is necessary for application programs running on the host computers to know which terminals are actually in session when they initiate a transaction, or an exchange of messages.
FIG. 12 is a block diagram that outlines a terminal management scheme in a conventional network computing system using front-end processors. This computing system is organized by host computers 31-33, front-end processors 37-38, and terminals 39-42. Terminal management files 34-36 are provided for the host computers 31-33, respectively.
The front-end processors 37 and 38 provide links among the host computers 31-33 and the terminals 39-42 by mediating between two different interfaces. FIG. 12 shows several connection paths as:
______________________________________ Host 31 --- FEP 37 -- Terminals 39, 40, . . . ! Host 32 -+- FEP 37 -- Terminals 39, 40, . . . ! +- FEP 38 -- Terminals 41, 42, . . . ! Host 33 --- FEP 38 -- Terminals 41, 42, . . . ______________________________________ !
where the terms "Host" and "FEP" denote "host computer" and "front-end processor," respectively.
For the host computers 31-33, the terminal management files 34-36 store the following information in a static fashion.
Unit identification numbers of their subordinate front-end processors and terminals PA0 Code system used in each terminal PA0 Performance level that indicates processing capability of each terminal
With their respective terminal management files 34-36, the host computers 31-33 obtain terminal information regarding any terminal, such as whether it is their subordinate terminal, what performance level it provides, and which code system it uses.
In this conventional system, however, the host computers 31-33 do not always have session status information of the terminals 39-42 at hand. The session status can be only obtained by having a conversation with each terminal. In other words, the host computer is unable to know whether the session is activated between each terminal and its corresponding front-end processor, in advance of transaction with that terminal.
Another problem in the conventional system is that the terminal management files have to be modified each time the system configuration is changed.